The inventive concept relates to holographic display apparatuses and, more particularly, to holographic display apparatuses capable of steering a view window.
Holographic display apparatuses may regenerate light wave of an object to make a three-dimensional (3D) image. The holographic display apparatuses may provide an actual image as shown through a mirror or a lens. A hologram 3D image may be a diffraction image of a coherent light, such that diffraction property of a light modulating device may greatly affect performance of the holographic display apparatuses. In principle, a volume and a view angle of the 3D image displayed by the holographic display apparatuses may be determined depending on a space-bandwidth provided by a spatial light modulating module. Thus, a device having very large space-bandwidth may be demanded for putting the holographic display apparatuses to practical use. However, performance of a current spatial light modulating device may be insufficient.
For enlarging a 3D space displayed by a digital holographic display apparatus, a view window may be limited to a pupil size of an eye so as to enlarge a size of the 3D space felt by an observer. This holographic display apparatus may demand an input optical system and an output optical system which randomly steer the view window according to a position of the pupil of the observer and provide the hologram image to both eyes of the observer. A function freely controlling the view window in all directions may be demanded in order that the observer naturally sees the hologram image.